What was one contribution made by eratosthenes in ancient greece? he wrote a geometry textbook that was used for nearly 2,000 years. he calculated the value of the infinite number known as pi. he computed the circumference of planet earth. he developed military tactics that still apply today.

One contribution made by Eratosthenes in ancient Greece was He computed the circumference of planet Earth. He was a Greek mathematician, astronomer, geographer, and poet. He invented the discipline of Geography. His calculation of the circumference of planet Earth was remarkably accurate, and he also calculated the distance from Earth to the Sun.

they were treated very badly. they were targeted by white supremacists and other groups, like the klu klux klan, even after coming back to the country as veterans. they were seen as inferior and gave the african americans new found motivation to fight against this racial injustice. 

can you tell me what is it